I'm not sure about that. I think that the sentence reads better if the "previously" is presented as a clause. "and, previously, video games" reads more naturally to me.
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Andy FJul 4 '11 at 11:07

2

I agree with @Jasper that "previously" should be weakly bracketed with commas. However, the improved punctuation does not remove an ambiguity. Does the OP mean that he has 5 years of commercial experience in developing cutting-edge websites and, previously, 5 years of commercial experience in developing video games? With the sentence as it is, I am left unsure about the nature and length of the video game experience the OP has. It might be better to write something like: "with 3? years of experience in developing video games, followed by 5 years of commercial experience in developing cutting
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ShoeAug 6 '11 at 7:45

This question addresses a similar problem, except with the conjunction "but", not "and" as here.

Basically, the same principles apply. Commas originally weren't used before conjunctions, but now they are. Thus, there is nothing wrong with your adding the comma behind "and". In fact, I would suggest: